AVR-Chat

Hein,
did you enabled the PIND.0 pull-up?

Regards

Jose

 --- kernels_nz <hein@mediflex.co.nz> escribió:

> Hi Ivan -- MORE INFORMATION !
> 
> Nope, using PIND.0 as general input, in fact, the
> plan is to use
> PIND.0 as general input to detect the start
> condition on a DMX512
> packet and then change it to to UART RX to receive
> the individual
> packets after that.
> 
> What I have done so far is look for the start
> condition (PIND.0 low
> for more than 80us) and just toggle one of the
> outputs everytime it
> receives a start condition. Doing this on PIND.0 is
> very erratic!
> changing the code only in such a way that I check
> any other pin, it
> works perfectly.
> 
> Another thing worth mentioning . . . I have noticed
> that PIND.0 is
> also starting to load my input signal for no
> apparent reason after a
> while of operation. The input signal is buffered,
> output swing is GND
> to 5V. After a while of running with this signal
> connected to PIND.0,
> the output swing measured with my scope droops to
> GND to approx 2.5V
> 
> Im starting to think more and more that the input
> signal is affecting
> the crystal clocking somehow, will try again tonite,
> and seperate them
>  as far as possible and also check the fuses etc. as
> some of the other
> guys suggested.
> 
> Thanks
> Hein B
> Auckland, New Zealand.
> 
> --- In AVR-Chat@yahoogroups.com, "Ivan Vernot"
> <ivernot@...> wrote:
> >
> > Hien,
> > Just a thought.... PIND.0 is shared with RXD on a
> mega16 - you don't
> have 
> > the UART enabled while you are trying to read
> PIND.0? ;-)
> > 
> > HTH
> > Ivan Vernot
> > 
> > 
> > ----- Original Message ----- 
> > From: "kernels_nz" <hein@...>
> > To: <AVR-Chat@yahoogroups.com>
> > Sent: Tuesday, February 07, 2006 8:19 AM
> > Subject: [AVR-Chat] Re: Problem reading PIND.0 on
> Mega16 with 16MHz
> Crystal
> > 
> > 
> > > Hi Guys, Thanks for all the suggestions, will
> check the fuses tonight
> > > when I get home, I think the suggestion that the
> input is actually
> > > affecting the crystal instead of the other way
> round sounds very
> valid.
> > >
> > > Im only checking PIND.0 as general input, and im
> reasonably
> > > experienced with AVR's , so dont believe it's a
> simple code problem.
> > > As I said, using PIND.0 = dont work, any other
> one of the PIND pins
> > > works fine.
> > >
> > > THANKS AGAIN ! GREAT SUGGESTIONS FROM EVERYONE !
> > >
> > > Cheers
> > > Hein B
> > > Auckland, New Zealand.
> > >
> > > --- In AVR-Chat@yahoogroups.com, "Dave VanHorn"
> <dvh@> wrote:
> > >>
> > >> > Could noise from the crystal pin be coupling
> to the data input
> > >> > and corrupting the data stream somehow ?
> could this be happening
> > >> > inside the Mega16 ? If so it is unfortunate
> that Atmel have
> placed the
> > >> >  RXD pin of the UART right next to the
> crystal pins.
> > >>
> > >> Far more likely that your input signal is
> disturbing the crystal.
> > >> If you haven't programmed the CKOPT fuse, then
> do so.
> > >>
> > >> After that, see my other post on checking the
> oscillator design.
> > >>
> > >> There are also possible layout issues,
> involving how the crystal caps
> > >> return to the AVR's ground pin. They should do
> so on an isolated
> track
> > >> that connects to system ground only at the AVR
> pin.
> > >>
> > >> > Unfortunately I really do need to use a 16MHz
> crystal also, so
> merely
> > >> > ignoring the problem and using a slower
> oscillator will not work !
> > >>
> > >> On a more mundane note, this may be a code
> problem, can you
> detail how
> > >> it is that you're checking the pin?
> > >>
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > > Yahoo! Groups Links
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> >
> 
> 
> 
> 
> 
> 
>  
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> 
> 
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>  
> 
> 
> 



	


	
		
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